Quite simple really; Hitler couldn't finish off Britain, he had been defeated. Even with that, Hitler always had his eyes on Russia, and attacking later would have been devestating. Russia was re-equipping its military, and would have been ready for 1942 which would have caused major problems for Germany. Operation Barbarossa was set for May 1941, the Russians wouldn't have been ready, and completely surprised. They thought how you are now ('They wouldn't attack Russia until finishing with Britain'). The Germans saw this as a perfect oppurtunity, and they were right to do it then. Russia had 4.7 million troops in June 1941, and only 25% were on the frontline with serious delays getting the rest to the front because of poor road and railway.

It was a very smart time to do it, and if they had attacked in May 1941 I dare say they would have won, avoiding the Russian winter.

I also think the Germans believed, incorrectly, that Britain had been neutralized. To a certain extent they were right, Britain was certainly NOT going to be launching an invasion anytime soon. Hitler was under the mistaken impression that he could quickly defeat the Soviet Union and the return to finish of Great Britain.

Hitler wasn't mistaken about anything to do with the Soviet Union, the one thing he was mistaken on was the British. And it cost him much, as he never thought an attack by the British would happen, and it did, in the Balkans delaying the attack on Russia by 6 crucial weeks

The Romanian oil fields weren't running dry. The economical reasons for invading Russia were many, but the reason for doing it when he did I stated above.
The main reasons were because of his hate of Slavs, the want of land and of course the economy. Taking out an enemy shouldn't always be missed as a reason.

The Soviet Union got kicked out of the league of nations after invading Finland. They weren't very good friends, but they found a common enemy in Germany.

Well the one thing that really made hitler lose the war was his stance with russia;after stalingrad he took away trains that took supplies to the front to send jews to deathcamps (more trains for the killing of jews instead of using them for reinforcing the eastern front.)It's logical.

One would think that Hitler would have remembered how poorly a second front turned out for Germany during WWI. Granted England wasn't a second front in 1941 but it was a massive base for bombers to wreck Germany's industry and a position from which a second front could be openned relatively easy.

Not to mention that the Germans lacked an effective long-range bomber to attack Soviet industry once it was moved past the Urals. You can also add to that the massive amounts of supplies the Western Allies shipped into the Soviet Union.

it doesnt, if you use that technique everything needs an apostrophie, that rule is only true for animate objects i think, but im not sure. what i am sure about however is that an apostophe is not needed there.

I'd invade Russia too if I had 3.5 million men under my banner, and a whole lot of technically and tactically minded men and machines. Being a lot smarter than Hitler, I would of won.
And you know I would have.